Force-Field Functor Theory: Classical Force-Fields which Reproduce Equilibrium Quantum Distributions

Feynman and Hibbs were the first to variationally determine an effective potential whose associated classical canonical ensemble approximates the exact quantum partition function. We examine the existence of a map between the local potential and an effective classical potential which matches the exa...

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Main Authors: Ryan eBabbush, John Anthony Parkhill, Alan eAspuru-Guzik
Format: Article
Language:English
Published: Frontiers Media S.A. 2013-10-01
Series:Frontiers in Chemistry
Subjects:
Online Access:http://journal.frontiersin.org/Journal/10.3389/fchem.2013.00026/full
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author Ryan eBabbush
John Anthony Parkhill
Alan eAspuru-Guzik
author_facet Ryan eBabbush
John Anthony Parkhill
Alan eAspuru-Guzik
author_sort Ryan eBabbush
collection DOAJ
description Feynman and Hibbs were the first to variationally determine an effective potential whose associated classical canonical ensemble approximates the exact quantum partition function. We examine the existence of a map between the local potential and an effective classical potential which matches the exact quantum equilibrium density and partition function. The usefulness of such a mapping rests in its ability to readily improve Born-Oppenheimer potentials for use with classical sampling. We show that such a map is unique and must exist. To explore the feasibility of using this result to improve classical molecular mechanics, we numerically produce a map from a library of randomly generated one-dimensional potential/effective potential pairs then evaluate its performance on independent test problems. We also apply the map to simulate liquid para-hydrogen, finding that the resulting radial pair distribution functions agree well with path integral Monte Carlo simulations. The surprising accessibility and transferability of the technique suggest a quantitative route to adapting Born-Oppenheimer potentials, with a motivation similar in spirit to the powerful ideas and approximations of density functional theory.
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spelling doaj.art-16bd4003568046a5a328d84f424cac862022-12-21T23:36:05ZengFrontiers Media S.A.Frontiers in Chemistry2296-26462013-10-01110.3389/fchem.2013.0002665852Force-Field Functor Theory: Classical Force-Fields which Reproduce Equilibrium Quantum DistributionsRyan eBabbush0John Anthony Parkhill1Alan eAspuru-Guzik2Harvard UniversityThe University of Notre DameHarvard UniversityFeynman and Hibbs were the first to variationally determine an effective potential whose associated classical canonical ensemble approximates the exact quantum partition function. We examine the existence of a map between the local potential and an effective classical potential which matches the exact quantum equilibrium density and partition function. The usefulness of such a mapping rests in its ability to readily improve Born-Oppenheimer potentials for use with classical sampling. We show that such a map is unique and must exist. To explore the feasibility of using this result to improve classical molecular mechanics, we numerically produce a map from a library of randomly generated one-dimensional potential/effective potential pairs then evaluate its performance on independent test problems. We also apply the map to simulate liquid para-hydrogen, finding that the resulting radial pair distribution functions agree well with path integral Monte Carlo simulations. The surprising accessibility and transferability of the technique suggest a quantitative route to adapting Born-Oppenheimer potentials, with a motivation similar in spirit to the powerful ideas and approximations of density functional theory.http://journal.frontiersin.org/Journal/10.3389/fchem.2013.00026/fullDensity Functional Theoryeffective potentialspath integral molecular dynamicsnuclear quantum propagationliquid hydrogen
spellingShingle Ryan eBabbush
John Anthony Parkhill
Alan eAspuru-Guzik
Force-Field Functor Theory: Classical Force-Fields which Reproduce Equilibrium Quantum Distributions
Frontiers in Chemistry
Density Functional Theory
effective potentials
path integral molecular dynamics
nuclear quantum propagation
liquid hydrogen
title Force-Field Functor Theory: Classical Force-Fields which Reproduce Equilibrium Quantum Distributions
title_full Force-Field Functor Theory: Classical Force-Fields which Reproduce Equilibrium Quantum Distributions
title_fullStr Force-Field Functor Theory: Classical Force-Fields which Reproduce Equilibrium Quantum Distributions
title_full_unstemmed Force-Field Functor Theory: Classical Force-Fields which Reproduce Equilibrium Quantum Distributions
title_short Force-Field Functor Theory: Classical Force-Fields which Reproduce Equilibrium Quantum Distributions
title_sort force field functor theory classical force fields which reproduce equilibrium quantum distributions
topic Density Functional Theory
effective potentials
path integral molecular dynamics
nuclear quantum propagation
liquid hydrogen
url http://journal.frontiersin.org/Journal/10.3389/fchem.2013.00026/full
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AT johnanthonyparkhill forcefieldfunctortheoryclassicalforcefieldswhichreproduceequilibriumquantumdistributions
AT alaneaspuruguzik forcefieldfunctortheoryclassicalforcefieldswhichreproduceequilibriumquantumdistributions